I have two altered adult rabbits (both over one year)--male (William) and female (Lily)--who live in separate condos in the same room. I have been working with them to bond them for a couple of months. Lily is the sweetest, most docile and passive rabbit I have ever seen, and she is very enamored with William and very submissive and polite around him. William actually "chose" Lily at a rabbit rescue; in the pen where they were introduced, he took to her right away, groomed her and layed next to her. In the bathtub (and in other small neutral territories), William is calm and accepting of Lily, even sprawling out next to her and occasionally grooming her. However, William's behavior changes dramatically when he and Lily are on less neutral territory, like in the bonding pen in their room (which they both have the opportunity to explore--separately--at other times). He thumps and growls at her, bites her, pulls out hair. Sometimes they'll be lying next to each other and he just bites her on the side, with no obvious provocation. He is very territorial and rubs his chin all over everything in their room when he is out. And about a week ago, he broke through to Lily's side of the room (both were out with the room divided in half by an unfolded pen), and attacked her aggressively. There was enough fur on the floor to build another rabbit. Luckily, Lily has no open wounds.

Is it possible that William is simply an antisocial rabbit who is not interested in having a friend? When I adopted William, he arrived with the brother who he was raised with. Although they were fully bonded for months--and altered--they eventually began fighting viciously and I had to rehome Henry. When I adopted Lily, I thought that William's "choice" of her suggested that we would have better luck with the relationship. But I am starting to become disillusioned. I feel especially bad because if Lily had her way, they would be best friends. Any suggestions?   

I do not have any additional space in my house where I can house the rabbits for lengthy periods of time. I feel lucky to have an extra room for the bunnies as it is. I have a dog who is quite aggressive and has a strong chasing instinct, so I have essentially divided my house into the general (dog-ok) living space, and the bunny's living space.

Ok, I'll give that a shot. Do you mean I should put them both into the new neutral space after the car ride and leave them in there together? I feel like I'd have to watch them closely to prevent any further aggressive behavior. I wouldn't want a fight to break out while I'm not hovering over them. I suppose I could do it on a Saturday morning and just hang out in the bunny room all day long, keeping my eye on them... What do I do if a fight breaks out? Do I do this repeatedly (reintroducing them to the "new" neutral space)?